Process of making tappets



Sept. 25,1923. 1,468,927 W. H. SPIRE PROCESS OF MAKING TAPPETS Filed 001:. 25. 1919 2 Sheets-Sheet 1 y jzzzrezziqr:

Sept. 25, 1923.

w. H. SPIRE PROCESS OF MAKING TAPPBTS Filed Oct. 25 1919 2 Sheets-Sheet 2 Patented Sept. 25, 1923.

, 1,468,927 UNITED STATES PATENT, OFFICE.

WILLIAM H. SPIKE, OF CLEVELAND, OHIO, ASSIGNOR TO THE STEEL PRODUCTS COK- PANY, OF CLEVELAND, OHIO,

A CORPORATION OF OHIO.

PROCESS OF MAKING TAPPETS.

Application filed October 25, 1918. Serial No. 838,187.

To all whom it may concern:

Be it known that I, WILLIAM H. SPIKE, a citizen of the United States, resident of Cleveland, county of Cuyahoga, and State of Ohio, have invented new and useful improvements in Processes of Making Tappets, of which the following is a specification, the principle of the invention bein herein explained and the best mode in whic I have contemplated applying that principle, so as to distinguish it from other inventions.

My invention relates to tappets used in connection with the operation of valves, and particularly valves used in internal combustion engines, and also to processes of manufacturing same.

The object of the invention is the production of a tappet having the requisite strength, of a minimum weight and having such characteristics embodied in its material structure as will allow a maximum life of the bearing surfaces, in an economical and efiicient manner.

The said invention consists of means and a method hereinafter fully described and particularly set forth in the claims.

The annexed drawings and the following description set forth in detail certain means and a method embodying my invention, the described means, however, constituting but one of the various mechanical forms in which the principle of that part of the invention may be employed.

In said annexed drawings:

Figure 1 represents an axial section of the two elements which are used in the production of the finished tappet.

Figure 2 represents a similar view showing said two elements welded to each other and before the final finished form is imparted thereto.

Figure 3 represents a similar section showing the tappet in its final and completed form.

Figure 4 represents an axial section of an alternative form of tappet embodying certain' features of my invention.

Figure 5 represents a cross section upon the plane indicated by line V-V in Figure 4.

In carrying out my invention,- I first form a hollow cylindrical stem ortion 1 and a separate head portion 2. aid stem portion is made from steel having a comparatively low carbon content,-say for instance a carthese threads, in this particular form of tappet, being used to receive one end of a threaded guiding rod, as will be understood by those skilled in the art.

The mushroom head ortion 2 is also formed of a comparative y low carbon steel, it being preferable to employ a chrome nickle steel having a carbon content similar to that of the stem portion. The boss 5 of this head portion, as is shown in the drawings, Figure 1, is hollowed out as at 6, so as to reduce the weight of metal.

After the head and stem elements have been formed as above described, I then carbonize the exterior superficial portions of both head and stem, leaving the end 7 of the boss 5 of the head and the outer end 8 of the stem portion of greater interior diameter in an uncarbonized or low carbon state. This may be done in any manner well known to those skilled in the art, as for instance by packing those parts which it is desired to retain in the low carbon state, in clay during the carbonizing process. In this illustrated instance, I leave about 5" or 5} of the stem in a low carbon state, and all of the head excepting the flat circular end portion, which is to receive the contact of or wear from the usual actuating cam of the engine.

In this manner, I provide a carbonized exterior wearing portion 9 on the stem and a carbonized exterior wearing portion 10 on the end of the head, these carbonized portions being indicated on the drawings by the double sectioning.

After such carbonizing process has been completed, the uncarbonized ends 7 and 8 of the boss and stem respectively are then welded, preferably by electric welding, and in this welding process pressure is applied in the direction of the axis of the tapp and the uncarbonized metal extruded both inwardly and outwardly, as shown in Figure 2. i

Where it is desired to have the entire exterior surface of the ta pet of carbonized or hard steel, substantia ly the entire head portion may be carbonized, leaving only the end of the boss in an uncarbonized condition, and the weldin process and pressure incident thereto may he carried on to such an extent that substantially all of the uncarbonized metal left in the structure after welding will have been extruded and the carbonized metal of both head and stem caused to substantially come into contact with each other. However, for ordinary purposes, the method first described is used.

After the welding process has been completed, the exterior of the tappet is then machine finished to nearly its final form, then hardened and ground to is final form, which is illustrated in Figure 3, in which the hard wearing surface of the stem portion is defined by shoulders 11 and 12, Figure 3. The interiorly extruded metal 13 is permitted to remain in place and forms a reinforcement for the welded joint. The required threads 14 are formed in the outer end of the stem, as also shown in Figure 3.

In this manner, it will be seen that the above described process permits'the major portion of the interior' bore of the tappet to have a maximum diameter and hence the major portion of the shell to be of a minimum thickness, at the same time permitting sufficient metal to remain at the outer end of the stem to form the necessary threads, this metal being comparatively soft and a1- lowing suchthreads to be readily cut. The carbonizing process is carried on to an extent sufiicient to produce the necessary depth of the wearing surfaces, usually to sue an extent as will produce a carbon content of .85.

It will also be noted that bv limiting the depth to which the carbonization is permitted to extend, the interior of the stem of the finished tappet is composed of soft and hence tough steel which acts as a reinforcing backing for the hard and brittle steel of the exterior. By limiting the location of the carbonization, as described, the fillet portion 19 which receives the maximum stress due to fiexure during the actuation of the tappet, is also composed of soft and tough steel best calculated to resist such stress and prevent breaka e at such point.

An a ternative form of tappet embodyinrr my invention is shown in Figures 4 and 5. In this tappet, the stem portion is formed with a transverse web 15, which separates the inner and outer bores thereof. The head and stem are welded, as before, after being carbonized, hardened and then finished to final form. In this form the outer bore is of a thickness such as is required. to give it the necessary strength, but is not formed -with threads. The guiding rod 16 merely slips loosely into this end and is adjusted to 1,4ea,e27

the pro r length by means of suitable shims 17. A ongitudinalinterior slot 18 is provided for the insertion of an instrument whereby these shims ma be removed from this bore when desired, a l as will be readily understood.

What I claim is:

1. The steps in the process of manufacturing a ta'ppet, which consist in providing a head low car n steel; providing a hollow stem mainly of hard steel but having an end portion of low carbon steel; welding such low carbon boss and low carbon end of said stem and extruding the low carbon metal so as to bring the high carbon metal of both head and stem substantially into contact.

2. The steps in the process of manufacturing a tappet, which consistin providing a head and a stem with terminal portions of low carbon steel, carbonizing the wearing surfaces and then welding such terminal portions to each other.

3. The steps in the process of manufacturing a tappet, which consist in taking a head and a stem of high carbon steel and provided with terminal portions of low carbon steel; welding such latter portions to each other and substantially eliminating the low carbon steel.

4. The steps in the process of manufacturing a tappet, which consist in taking a head and a stem of high carbon steel and provided with terminal portions of low carbon steel; welding such latter portions to each other and extruding the portions of low carbon steel laterallyso as to substantially eliminate such low carbon steel from the body of the tappet.

5. The steps in the proces of manufacturing a tappet, which consist in forming a separate head and stem of comparatively low carbon steel; increasing the carbon content of such head and stem with the exception of terminal portions; and then welding such terminal portions to each other.

6. The steps in the process of manufacturing a tappet, which consist in forming a separate head and stem of comparatively low carbon content; increasing the carbon content of such head and stem with the exception of terminal portions; then welding such terminal portions to each other and extruding the low carbon steel laterally so as to bring the high carbon metal of both head and stem substantially into contact.

7 The process of manufacturing a ta pet, which consists in forming a separate head and stem portion, each of comparatively low carbon content; drilling out the stem rtion so as to form a comparatively thin s ell but leaving an end portion of greater thickness; increasing the carbon content of the exterior superficial portion of both head and stem with the exception of terminal porortion of hard steel with a boss of tions thereof; and welding such terminal portions to each other.

8. The process of manufacturing a tappet, which consists in forming a separate head and stem portion, each of comparatively low carbon content; drilling out the stem portion so as to form a comparatively thin shell but leaving an end portion of greater thickness; increasing the carbon content of both head and stem with the exception of terminal portions; welding such terminal portions to each other, extruding the low carbon steel laterall and then removing such extruded low car on steel.

9. The process of manufacturing welded steel articles which consists in hardening the parts of the articles before welding but leaving terminal portions to be welded unhardened, and welding said unhardened portions together.

Signed by me this 16th day of October, 1919.

WILLIAM H. SPIRE. 

